Hard disk drives include one or more rigid disks that are coated with a magnetizable medium and mounted on a spindle hub of a spin motor for rotation at a high speed. Information is read from and written to each disk on a plurality of concentric tracks by a read/write head (“head”) mounted on an actuator arm. The outside circumference of each disk is referred to as the “outer diameter” (OD), and the center of each disk is referred to as the “inner diameter” (ID). A head is said to “fly” over the disk surface on an air bearing as the disk rotates. When disk rotational velocity decreases, the layer of air supporting the read/write head above the disk surface diminishes and the head descends toward the disk surface. Contact between the head and the disk surface can damage the magnetizable medium and the head. Furthermore, through a phenomenon called “stiction,” a head can become permanently or temporarily “stuck” to the disk surface after landing on the disk surface. Stiction can damage the magnetizable medium, the head, and/or the actuator arm when the disk drive system initiates disk rotation in an attempt to move the read/write head from the disk surface.
A contact-start-stop (CSS) configuration may be used to address this problem. A CSS configured disk drive responds to spin-down of a disk by moving a head over a CSS zone defined on the disk so that the read/write head lands on the CSS zone as the disk loses rotational velocity and lands thereon. The disk drive responds to spin-up of the disk by moving the head from the CSS zone back to data areas on the disk when the disk rotational velocity becomes sufficient to allow the head to fly above the disk surface.
The CSS zone should have a sufficient length and width to accommodate landing of the head thereon during spin-down of the disk and to accommodate the lift of the head off therefrom during spin-up of the disk. The CSS zone can have a textured surface that reduces contact area between the head and the CSS zone to avoid stiction.